In-Situ X-ray Absorption Spectroscopic Study on Variation of Electronic Transitions and Local Structure of LiNi_1/3Co_1/3Mn_1/3O₂ Cathode Material during Electrochemical Cycling

Abstract

In-situ X-ray absorption spectroscopic investigations have been carried out to examine the changes of the electronic transitions and local structure at the Mn, Co, and Ni K-edge for the LiNi 1/3 Co 1/3 Mn 1/3 O 2 electrode during charging and discharging process in this study. It was found that only Ni atom in Li 1-x Ni 1/3 Co 1/3 Mn 1/3 O 2 is electroactive from the evolution of the XANES spectra and the bond length variation of Ni-O. It was found that the redox pairs of Ni 2+ /Ni 3+ and Ni 3+ /Ni 4+ exist and the oxidation states of Mn and Co remain as Mn IV and Co III , respectively, in Li 1-x Ni 1/3 Co 1/3 Mn 1/3 O 2 upon charge and discharge. The oxygen, rather than the transition-metal ions (Ni, Co, and Mn), functions as electron donor at the end of charge. In addition, the irreversible capacity at the first cycle derives mainly from the appearance of inactive Ni, which is evidenced by the energy shift E -E 0 of the absorption edge for the Ni absorber and the bond length change of the Ni-O. A decrease/increase of Debye-Waller factor of Ni-O contribution results from a decrease/increase of Jahn-Teller active Ni III concentration during cycling. The trends of the variations for the bond length and Debye-Waller factor for the second shell Mn-M and Ni-M contributions are significant and similar, suggesting the short-range ordering between Ni II and Mn IV may take place in this compound.

Single-particle measurements of electrochemical kinetics in NMC and NCA cathodes for Li-ion batteries

“…3c. 27,37,38 Both show a similar linear decrease in unit cell volume with increasing SOC (increasing delithiation) at low SOC. However, the unit cell volume for NCA decreases sharply at higher SOC.…”

Synthesis of LiNi1/3Co1/3Mn1/3O2 cathode materials by using a supercritical water method in a batch reactor

“…Using the solid-state reaction, Song and co-workers [14] prepared cathode powders by calcination at 750 • C for 30 h after milling for 1 h and preheating in air at 450 • C for 5 h. With the combustion process [26], cathode powders could be obtained by calcinations at 750 • C for 24 h after heating at 90-100 • C for 1 h and drying at 120 • C for 12 h. In the case of sol-gel method [22], cathode powders were synthesized by calcination at 900 • C for 12 h after stirring at 80-90 • C for 5-6 h to form a viscous gel, which is then dried in a vacuum oven at 140 • C for 24 h. It was also reported that cathode powders were synthesized through the spray dry method with sintering at 900 • C for 20 h in air [28]. In this study, however, all cathode powder materials were synthesized by the SCW method in 10 min of reaction time without any further thermal treatment such as high temperature calcination or sintering.…”

“…However, this preparation process causes inhomogeneity, irregular morphology, large particle size, and broad particle size distribution, and it requires long heating times followed by several grinding and annealing processes [11]. Various synthesis methods have been applied to overcome these drawbacks which include the combustion process [5,25,26], the co-precipitation method [23,27,30], molten salt synthesis [20], the sol-gel method [8,22], the spray dry method [2,10,28], and spray pyrolysis synthesis [11,19,29].…”

An in situ synchrotron XAS methodology for surface analysis under high temperature, pressure, and shear

“…In addition to these in-situ techniques, there were numerous studies that utilized in-situ XAS to study the evolution over time of different materials such as catalysts [47,48], electrodes (cathode materials) of metal oxides [49,50] and tribofilms of oil additives [51,52]. Morina et al [51] and Ferrari et al [52] studied the evolution of ZDDP thermal films in-situ after different heating times using a heating cell combined with XAS.…”